N'DJAMENA, Chad (CNN) -- Some of the 103 children at the center of an alleged international kidnapping case may never return to their families because it is too difficult to determine their backgrounds, a Red Cross spokeswoman said Friday.
Hundreds of women protest child trafficking and shout anti-French slogans in Abeche, Chad.
The children are living in an orphanage in the eastern Chadian city of Abeche while aid agencies and government officials try to figure out where they came from, but the agencies have said the investigation is challenging because of the number of children, their young ages, and the volatile situation in the region.
Red Cross spokeswoman Inah Kaloga acknowledged Friday that it's possible some of the children will never be returned to their families.
Zoe's Ark, the French charity that organized the trip, has said the children were orphans from Sudan's war-torn Darfur region and the group was taking them to host families in France.
But after preliminary interviews with the children, aid agencies said Thursday it appeared most of them probably are not orphans and not from Sudan, but instead come from villages on the Chadian side of the border with Sudan.
Chad authorities arrested 17 Europeans and four Chadians last week as they attempted to load the children onto a plane to fly them to Paris.
Among those in custody are six Zoe's Ark members, all charged with kidnapping.
Three French journalists who were on the trip and a flight crew of seven Spaniards and a Belgian are also in custody, charged with complicity, along with the four Chadians.
All of the defendants were transferred from Abeche to N'Djamena on Friday. Omar Yahya, a spokesman for Chad's government, told CNN that investigators and the Minister of Justice in Abeche have transferred the case to the Supreme Court in N'Djamena.
Chad's president has expressed hope that the journalists and flight crew can be released, and a jurisdictional shift in the case would give the president the legal opportunity to intervene on their behalf, according to the president's chief of staff, Mahamat Hissene.
Watch CNN Senior International Correspondent Nic Robertson's report from Chad »
The Spanish government sent an ambassador to Chad to press for the flight crew's release, and the international press freedom group Reporters Without Borders said it will ask for charges against the journalists to be dropped.
Attorneys for the charity workers have said their clients are innocent. In a joint statement issued Thursday, the Red Cross, U.N. High Commissioner for Refugees (UNHCR) and UNICEF said most of the children were living with their families and at least one parent before Zoe's Ark took them to Abeche.
The UNHCR said it was interviewing the children and taking photographs of them. When that process is complete, the UNHCR said, it will pass the dossiers to the Red Cross, whose workers will go village to village along the Chadian-Sudanese border area to look for the children's families.
The UNHCR said some of the children have brothers or sisters in the group. The youngest child is a 1-year-old girl with no siblings in the group, and the UNHCR said tracing her background would be the most difficult.
The UNHCR has said the oldest child in the group is around 10, and most are between 3 and 5. Kaloga said the children are in good health, though some have been treated for minor injuries.
She said Chadian authorities are considering whether to move the children to the capital or leave them in Abeche. E-mail to a friend
CNN Correspondent Nic Robertson and Producer Sarah Sultoon contributed to this report
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